Need help! 617 N/A rattling louder after head gasket replacement - PeachParts Mercedes-Benz Forum

ROLLGUY · #1 10-05-2022, 07:51 PM

The car came to me with a leaking head gasket, as well as almost every other seal/gasket. Also, the engine was painted orange, so we decided to paint the engine bay while the engine was out. http://www.peachparts.com/shopforum/diesel-discussion/417458-how-not-install-crankshaft-seals.html After replacing all the seals/gaskets and painting the engine and bay, the rebuilt head was installed on the block, and the engine installed in the bay. After getting the engine running, it was knocking very loud. I re-adjusted the valves (several were loose), and retarded the injection timing a bit. I initially had it set at 24 degrees BTDC. I reset it to 23 degrees BTDC. It seemed to be a little quieter, but the #1 injector was louder than the rest. I replaced it with another one, and that quieted that cylinder down a little more. It still sounded like a rod knock, so I removed the lower pan and replaced the #1 con rod bearing. It did not look terrible, but I wanted to rule out a bad bearing. Please view the video and tell me what you think. Could it be too much compression? Could it still be too far advanced? (book calls for 23-25 degrees BTDC). I can't give the car back to the owner sounding like that.

https://youtu.be/e_KCy8a2_UM

t walgamuth · #2 10-05-2022, 09:39 PM

its not too much compression I don't think.

dieselbenz1 · #3 10-05-2022, 11:23 PM

Odd noise, those engines use a chain tensioner that needs to be reset I believe. Just a thought?

Sugar Bear · #4 10-05-2022, 11:38 PM

Was the head measured for minimum thickness? Was the head resurfaced? Is it the same head? Any guides replaced?

Remarkable job on the engine bay, it looks amazing!

ROLLGUY · #5 10-06-2022, 04:55 PM

Quote:

Originally Posted by Sugar Bear

Was the head measured for minimum thickness? Was the head resurfaced? Is it the same head? Any guides replaced?

Remarkable job on the engine bay, it looks amazing!

The head was surfaced, and exhaust valve guides replaced. The head is flat, so it does not matter if .001 or 1/4 inch is removed, it is still flat. The only thing that might matter is the prechambers. Thicker seals need to be used if needed. The only thing that might change the compression is a thinner head gasket. I used Elring, and have used that brand MANY times without issues.
I am leaning towards the timing still being too far advanced, even though it is at the minimum spec (23 degrees BTDC). That is with the adjustment of the pump all the way at maximum without removing it (done after the last removal and retarding of the pump). I may take the time to remove and retard the pump even more. I am now just "grasping at straws" here, and don't know what else to do. In the almost 20 years of working with these cars, I have never heard of this problem, nor experienced anything like this.

ROLLGUY · #6 10-06-2022, 04:58 PM

Quote:

Originally Posted by dieselbenz1

Odd noise, those engines use a chain tensioner that needs to be reset I believe. Just a thought?

Only the turbo has the ratcheting tensioner (has to be reset if tension is removed). The N/A only has a spring with hydraulic (oil) assist.

BillGrissom · #7 10-06-2022, 05:04 PM

Have you measured compression? (I know, tougher on a diesel engine). Unless you shaved the head or somehow used a thinner head gasket, I don't know how it could be too high. I know that in gas cars, the camshaft used and its clocking (some timing-sets allow up to 7 settings on the timing sprockets) can change compression. The concern for racers is getting too high a compression (>200 psig) so the starter can't easily crank over the engine. Anyway, re-verify the valve timing marks. I added a 4 deg offset key in my two engines to get it perfect (or slightly advanced), to account for timing chain wear.

I set my two 300D's for 27 deg BTDC "start of injection". It can be a little tricky to measure it perfectly, and people here get too hung up on the "1 drop per sec" method. All you are trying to do is find the crank location where the #1 injection pump piston first closes the inlet valve to "start injection". It is a very sharp location, whether you count drops or not. Setting earlier than the spec 24 deg is supposed to give better performance at the expense of slightly more idle noise, but I didn't notice a difference.''

The youtube sounds like a normal idle to me. I doubt the noise is internal since bad rod or crank bearings usually give a deep sound. Yours sounds like normal combustion noise. The fuel can make a big difference. I notice a much quieter idle when I fuel with "renewable diesel", which claims a higher cetane rating. From 20 ft away when idling, you can barely tell the car is a diesel. When my daughter fueled with fossil diesel recently, the idle was noticeably louder. You are in CA, so can buy Propel's Diesel HPR or Union 76 R99. They are bio-based, but work in any diesel vehicle (no mod's needed). Union 76 stations that carry it have ad banners "Renewable Diesel" (or did).

fauxwiehl · #8 10-06-2022, 07:26 PM

Pretty certain the owner has been filling up with renewable at 76. But that wouldn't mean much unless they were all uniform in behavior. I believe a new timing chain was installed as well, at least he said he was going to and it's logical to do that during the head swap.

Throwing any ideas out no matter how unlikely they may be...
I figure you're pretty certain it's coming from #1. My work wagon was making a sound like nailing. Ended up not being the injector, but a worn intermediate shaft bearing and the rollercoaster follower was kicking the plunger inside the vac pump enough to blow the bearings and snap the piston/plunger(probably not good for the IP on the other end). Shot in the dark, but it's something to rule out at least. And my rebuilt injectors in my 77 300D were kinda loud at first, though they were uniform(I assumed). At 106K the chain is not a factor, though I did adjust valves for the second time in 1,000 miles as they were both tight and loose when I bought it at 104K, and also pump timing a bit to quiet things down and fix the smoke. Sound is pretty much "gone" now, 500 miles later.

Jarod · #9 10-07-2022, 11:51 AM

My Blue car had a weird sound for a while, turned out to mostly be the cam lobes wearing down and causing the rocker arms to hammer into stuff and rattle around, turns out it was run low on oil due to a turbo drain hemorrhaging oil.

I swapped the cam out, which massively quieted it down, but there was a lingering rhythmic knock sound. I replaced the injector nozzles, and got them all popping within maybe 25psi or so of eachother, then installed them, it had a much louder combustion clatter, which faded a little after running it for a few hundred miles, noise is basically normal I'd say now, and I've driven it thousands of miles with no issues.

Backstory aside, my engine has a little rock at idle like yours does in the video. I have suspected that I need to check my injectors again, or I might have a weak cylinder, or the cam wear has caused something else to have an issue, perhaps one of the plungers/barrels in the injector pump is scored from the oil starvation event.

I wish there was a good way to measure IP output on the car, test if all 5 cylinders are getting equal fuel, but I'm unaware of any way to do that. Maybe a infrared camera and look at the exhaust to see if one hole is colder or hotter than the others?

I wonder if the head gasket going bad on the engine you're working on could have damaged something else, coolant got somewhere it shouldn't or is it possible it hydrolocked even a tiny bit and bent a rod?

A compression test while not terribly fun might give some ideas.
Sorry to ramble, I am curious what the end result is, as it might help me track down my rhythmic rocking that a rack damper did not help.

I feel like that little rock indicates one cylinder is either contributing more than the others, or possibly less.

ROLLGUY · #10 10-07-2022, 02:00 PM

Thanks for all the guesses. If I had another N/A engine handy to compare the sound with, I am sure you could tell that this one is louder in a video. I think my Iphone captured the sound pretty good. I did install a new timing chain, so that is ruled out. The engine is using the same lower end (block, crank, pistons, rods, injection pump etc.) that it drove in on. It was very quiet for an N/A. It had a sedan head on it, and the owner wanted to get his SLS working again. He found a good wagon head, and my machine shop rebuilt it (they have done at least a dozen 617 heads for me). I used the original 115 bar injectors. However, thinking that the loud rhythmic sound was from #1, I replaced it with another 115 bar injector I had. The sound did not seem as loud. Also, feeling each injector line close to the injector, it felt like #1 was hitting harder than the rest, so I changed it. The fuel is the same that was in the tank when the car drove in. The vacuum pump has been changed, so I think I will remove it and have a look at the "roller coaster". That might contribute to the noise if it is worn out. After checking that, I might retard the pump one tooth and see if that quiets it down any. The engine seems to start and run fine even at the 23 degrees (or -) that it is set to now.

EDIT:The N/A does not have a rack damper bolt to adjust.

hercules · #11 10-07-2022, 02:09 PM

Verify T.D.C. #1 cyl. with block pointer. Mine was off 3 degress.

ROLLGUY · #12 10-07-2022, 04:53 PM

Quote:

Originally Posted by hercules

Verify T.D.C. #1 cyl. with block pointer. Mine was off 3 degress.

Done- everything lines up perfectly. That was the FIRST thing I checked after hearing the noisy engine.

hercules · #13 10-07-2022, 07:13 PM

There was a few of the injection pumps miss marked,there was a bulletin about.
Seems, by sound the engine has a harshness,as if over advanced.

ROLLGUY · #14 10-07-2022, 09:48 PM

Quote:

Originally Posted by hercules

There was a few of the injection pumps miss marked,there was a bulletin about.
Seems, by sound the engine has a harshness,as if over advanced.

Agreed, it does sound like it's advanced too much. That is what I am leaning towards, even though it is already retarded a little more than the minimum spec. It is running the same IP that the car drove in on, and it was quiet when it arrived.

shadetreemechan · #15 10-08-2022, 08:15 AM

Quote:

Originally Posted by ROLLGUY

Agreed, it does sound like it's advanced too much. That is what I am leaning towards, even though it is already retarded a little more than the minimum spec. It is running the same IP that the car drove in on, and it was quiet when it arrived.

Some pumps have the timing mark in the wrong location, so even if its the same pump, if it was set up to accommodate the error before and you installed it as if it were a normal pump, your timing will still be off. I found out about the incorrect timing marks in the FSM when I was working on a 240. I am sorry but I can't remember how you determine which ones are off, but the information is out there.